Audio radios generally receive and process radio frequency (RF) signals typically in the amplitude modulated (AM) or frequency modulated (FM) radio bands. FM/AM audio radios are commonly employed in various environments including on board automotive vehicles. In addition to receiving FM and AM radio bands, some vehicle radios incorporate a receiver that is further capable of receiving weather (WX) band signals. The National Oceanic and Atmospheric Administration (NOAA) broadcasts the weather band radio service in the United States. The NOAA weather band broadcast transmissions generally include seven narrow band frequency modulated channels in the very high frequency (VHF) band at frequencies ranging from 162.40 kHz to 162.55 kHz, with a 25 kHz channel separation between adjacent channels.
The NOAA weather band signals include weather and emergency alert data pertaining to local geographic regions which serves as a broadcast warning alert system. The NOAA weather band broadcast includes specific area message encoding (SAME) transmitting a coded message using audio frequency shift keying (AFSK). The SAME message provides digital information indicative of the geographic region covered by the accompanying message and the warning alert data. The warning alert data includes warning alerts related to weather such as warnings or watches for tornadoes, tsunamis, hurricanes, winter storms, flood warnings, and other weather related events. Additionally, the weather alert data includes non-weather related events, such as child abduction emergency warnings, civil danger warnings, civil emergency messages, earthquake warnings, evacuation warnings, fire warnings, amongst other non-weather related warnings.
With the conventional AM/FM/WX band radio, a user may select one frequency at a time from one of the available radio bands. If a user would like to acquire the weather band signal and its warning alert data, the user is typically required to select the weather band by activating a switch which tunes the tuner to the weather band. Once the weather and warning alert data information is no longer desired, the user must select the AM or FM band to return to the original radio band station.
The radio data system (RDS) in Europe broadcasts the identical information on multiple frequencies such that the same radio content can be provided in a vehicle as the vehicle travels from one broadcast frequency region to a different broadcast frequency region. In doing so, the RDS employs an alternate frequency (AF) update to periodically look for better quality alternate frequency broadcast signals. The radio stations generally are linked by the RDS data, which identifies each station as being on the network and contains a list of the alternate frequencies on the network. As the vehicle travels, the radio automatically monitors the signals at the alternate frequencies and decides if it should switch to a station providing a better quality signal in the list of alternate frequencies. In a receiver having a single tuner, the radio monitors the stations in the list of alternate frequencies by quickly tuning from the current station to another station in the list of alternate frequencies and then back to the original station. During the quick tuning to the alternate frequency, the radio collects statistics, which generally determine the signal quality of the alternate frequency station. While the RDS configured receiver is able to monitor other stations, particularly with a single tuner, it does so in order to provide the same identical program information.
It is therefore desirable to provide for a cost affordable radio and method of monitoring data in an alternate band, such as the weather band, for providing warning alert data in a manner that does not require multiple tuners. In particular, it is desirable to provide for such a radio and method for use in a vehicle to monitor the warning alert data made available on the weather band in a way that does not interfere with the current radio station programming.